1. Field of the Invention
The present invention relates, in general, to roller coasters and other amusement park rides, and, more particularly, to systems and methods for selectively and accurately controlling the speed and, thereby, the energy of cars or vehicles carrying passengers in an amusement park ride at specific locations such as during a show portion of the ride in which visual and/or audio effects are provided as part of the ride experience or to control the overall energy of the vehicle to ensure consistent and safe system performance.
2. Relevant Background
Amusement parks continue to be popular worldwide with hundreds of millions of people visiting the parks each year. Park operators continuously seek new designs for extreme or thrill rides because these rides attract large numbers of people to their parks each year, and roller coasters and other thrill rides provide numerous twists, turns, drops, and loops at high speeds. However, in addition to high-speed or thrill portions of rides, many rides incorporate a slower portion or segment to their rides to allow them to provide a “show” in which animation, movies, three-dimensional (3D) effects and displays, audio, and other effects are presented as vehicles proceed through such show portions. The show portions of rides are often run or started upon sensing the presence of a vehicle and are typically designed to be most effective when the vehicle travels through the show portion at a particular speed.
For example, a roller coaster may be designed such that in a show portion dinosaurs attack the vehicles, meteors fly toward the passengers, animatronic figures perform, and the like. The show may be designed based on the anticipated speed of the vehicle after it enters the show portion such that an effect such as 3D “attack” on the vehicle occurs precisely when the vehicle is adjacent to a portion of the display screens, speakers, and/or other show equipment. Some 3D imagery is achieved with a screen that rotates with the passing vehicle to maintain the desired effect and such rotation requires that the vehicle be traveling at a known speed. Other rides are designed such that the show includes jets, streams, and other water effects that require knowledge of vehicle position and speed to achieve desired effects such as water passing near passengers without striking the passengers or vehicle. Other rides are used to tell stories, and it is desirable to control the speed or pace of the vehicles during show sections of the ride so the passengers can enjoy the set, which may include special effects that are sensitive to or synchronized to vehicle speed (e.g., a multimedia presentation may actually be intentionally distorted such that it appears normal to passengers in a vehicle when the vehicle is moving at a particular speed but when the vehicle is moving too fast or too slow the distortion may be seen). Ride designers or engineers are given the task of producing unique and more exciting rides that mix thrill and show portions in which both portions of the ride are effective while also providing rides that are less costly to operate and maintain.
To date, controlling speed of vehicles in amusement rides to the degree of accuracy demanded by show designers has proven difficult especially in the case of roller coasters. A roller coaster is made up of a number of cars or vehicles that are connected like a passenger train, but roller coasters are typically not self-powered. Instead, for most of the ride, the train or vehicles are moved by gravity and momentum. To build up potential energy, a chain or cable is used to lift the train to a first peak or lift hill and the train is released with its potential energy becoming kinetic energy as the train accelerates to a high velocity in the first downward slope. The initial potential energy is enough to complete the entire track or course of the ride, and the train is stopped by mechanical or magnetic brakes that remove any remaining kinetic energy. In some cases, the train is set in motion by a launch mechanism such as a flywheel launch, a linear induction motor (LIM), a linear synchronous motor (LSM), a hydraulic launch, and the like that apply a force to the captured train to rapidly bring the train up to a kinetic energy or velocity that allows the train to complete the entire ride.
Mechanical systems called pacers are used by ride designers to adjust the speed of roller coaster trains or vehicles for the primary purpose of controlling the energy in the system. The pacer can speed up a slow vehicle or slow down a fast vehicle to provide more consistent and safe performance of the ride system. Pacers can also be used in show portions or sections of the ride course or track to control the speed of a vehicle through a specific scene in order to achieve a desired experience. Mechanical pacers typically include a number of wheels driven by motors at a certain velocity. Tires on the spinning wheels contact the vehicles (e.g., pinch a fin on the bottom of the vehicle), and the physical contact or friction forces cause the vehicle to slow down by removing kinetic energy or speed up by adding kinetic energy (e.g., slow to a speed or velocity in a range at or approaching the velocity of spinning wheels or speed up). In some cases, potential or kinetic energy is added after the mechanical pacer so that the train can complete the course. Potential energy may be provided by again mechanically lifting the train up a second lift hill or kinetic energy may be added through re-launching such as by using a LIM or LSM to capture the train and then apply a magnetic force to the train in the direction it is traveling to accelerate the vehicle to a desired launch speed.
While the train of vehicles generally will slow down or speed up to a velocity at or near the velocity of the spinning wheels, there are a number of problems with using mechanical pacers for rides that include a show portion. Mechanical pacers rely on physical contact, such as between spinning tires (e.g., rubber tires or the like) and a metal fin, to slow or speed up the vehicles, and the contact causes wear that leads to ongoing maintenance including part replacement. This increases costs associated with using a mechanical pacer as its life cycle is reduced especially on rides that experience a high duty cycle (e.g., many cars per hour). The wear also results in the performance of the mechanical pacer varying over time, which causes the performance of the pacer to change such that vehicles may be slowed or sped up less as the pacer experiences wear causing the velocity to be higher or lower than desired during a show portion of a ride. Mechanical pacers also require a large space for mounting of the motors, wheels, and other components. Further, maintenance of a particular pacer unit may require that the unit be lowered into a pit provided under the ride, and such pits also are costly to build and use valuable real estate in the design of a ride. Further, mechanical pacers are typically only useful in relatively long flat and straight sections of track that allow for the fin and friction wheels to properly engage and allow for the large size of the pacer units. Hence, the use of mechanical pacers reduces the freedom of a ride designer because show portions can typically only be provided in straight portions of the ride, and the ride designer also has to build long straight sections of track into the ride rather than providing a ride just with curves or with more curves, which may be desirable for creating unique ride experiences and is also useful for fully utilizing available space or real estate.
Additionally, mechanical pacers operate at one speed with each contacting tire being spun at the same rate, but the vehicles enter the mechanical pacers at a range of speeds. On a roller coaster ride, there are often a number of trains that are run sequentially but spaced apart. While following the same course, each of these trains (e.g., set of cars or vehicles) likely will complete the course in a different amount of time due to differences in the vehicles and due to varying weight of the passengers. Further, the same train typically will likely travel at different velocities each time it travels through the ride due to changes in the passenger make up and other variables. As can be seen, parameters such as temperature, wheel and track wear, train weight, passenger weight, wind, rain, and the like can alter the speed at which a train proceeds through a roller coaster coarse, and as a result, the speed at which the train enters the mechanical pacer varies. For example, a mechanical pacer relies wholly on friction to adjust a speed of a train, and the ride may actually have to be shutdown during periods of rain as the friction is reduced below a minimum value, and the ability of the mechanical pacer to accurately control speed is significantly reduced as the friction applied varies from its design value. The mechanical pacer, however, continues to operate at its one set pace or operating speed as it is essentially a dumb system with a single setting, and this results in a range of train speeds being produced by the mechanical pacer as trains with higher entry velocities exiting at higher velocities than trains with lower entry velocities. As a result, the show experience of the passengers is not consistent and may be different each time a passenger gets on a ride.
Hence, there remains a need for improved pacers for controlling the speed of vehicles or cars of amusement park rides such as roller coasters. Preferably, such pacers would be effective for controlling the speed/energy of vehicles throughout the ride cycle as well as in specific show portions of the ride within an acceptable range about a goal velocity or show design velocity while being relatively inexpensive to implement and maintain. Additionally, it is desirable that the pacer be useful in applications for which mechanical pacers are not well suited such as in sloped and curved sections of track such that the show portions of a ride are not limited to flat, straight sections.